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Prepared by 

Richard E. Sparks 

Illinois Natural History Survey 

River Research I,^boratory 

Havana, Illinois 62644 

Revised June 18, 1977 

for the 

Subcommittee on Soil Erosion and Sedimentation 

Illinois Task Force on Agriculture I'onpoint Sources of Pollution 

Reduction of Light Penetration 

Primary production is the production of organic material from carbon 
dioxide and water by green plants and is the basis for all food chains in 
both aquatic and terrestrial environnents. Primary production is the re- 
sult of a process called photosynthesis, which is dependent on sunlight. 
In aquatic environments, primary production occurs only in the euphotic 
zone, as the result of photosynthesis by both floating and attached algae 
and by higher plants. Below the euphotic zone, there is not enough 
light to permit green plants to produce more food by photosynthesis than 
they consume in the process of respiration, so there is no primary pro- 
duction. The euphotic zone extends down to the depth at which the light 
intensity is approximately 1 percent of what it is at the surface. In a 
shallow lake, the entire lake may lie within the euphotic zone. One effect 
of suspended sediment is to reduce the euphotic zone, thereby reducing 
primary production. Claffey (1955: 24) used a spectrophotometer to 
measure light penetration in waters of various turbidities. In water 
having a turbidity of 25 JTU, only 24.9 percent of the original light 

of the red wave lengths (the most penetrating) was visible at a depth 

of 4 inches; at 50 JTU, only 6.3 percent; and at 150 JTU, no light was 

available at a depth of A inches. 

In farm ponds, lakes, and large J-mpoi'ndments primary production within 

the water itself can be the major source of food for the entire aquatic 

ecosystem. Waterfowl feed directly on many species of aquatic macro- 

phytes. Few species of fish feed directly on phytoplankton or raacrophytes. 

Some fish, such as gizzard shad, feed on the zooplankters (microscopic 

animals) which in turn feed on phytoplankton. Many of the garaefish 

consume zooplankton when they are small, then graduate to insects and forage 

fish as they become larger. The effect of turbidity on plankton was 

measured by Claffey (1955: 43), who used .i Wisconsin-type plankton 

net with No. 25 mesh silk bolting cloth to sample 20 farm ponds of varying 

turbidity in Oklahoma. Zooplankton probably com.prised the bulk of the 

material collected by the net. Turbid ponds contained much less plankton 

in the surface waters (0 to 2 feet) than clear ponds: 

Volume (ml of plankton Reduction of plankton, in 
Turbidity Class per liter of water ) comparison to clear water 

Clear ( 25 JTU) 0.0187 

Intermediate (25-50 JTU) 0.0037 80% 

Muddy (51-350 JTU) 0.0019 90% 

Primary production can be a nuisance when it is in the form of algal 
blooms which are unsightly or cause taste and odor problems in drinking water. 
Suspended sediment can limit or prevent such blooms by reducing light penetra- 
tion and adsorbing nutrients, such as phosphorous, which stimulate plant growth. 
Such blooms might occur in many bodies of water in Illinois if suspended 
sediment levels were reduced without also reducing levels of plant nutrients. 



Fic. © Tuibidities of Lake Chjutauqua occurring 
at various wind velocities (average maximum oae 
hour preceding collection time ) in the absence and 
presence of vegeUtion. The graph shows that w-ind 
has litde or no effect upon turbidity of Lake Chau- 
tauqua when vegetation is present 

Plant nutrients enter water from many sources, in addition to agricultural 
sources. For example, phosphorous is used in detergents and contributes to 
high phosphorous levels in effluents from sewage treatment plants. 

In streams and rivers, primary production in the terrestrial environ- 
ment is a major source of organic material, which is dropped, blown, or 
washed into the aquatic environment. 

In aquatic environments, higher plants have other functions in addition 
to the function of producing food. Their roots can anchor the bottom against 
wave action and against the rooting activities of bottom-feeding fish such 
as carp. The stems and leaves of floating and emergent plants dampen waves. 
Therefore plants can reduce turbidity by preventing resuspension of bottom 
sediments by waves or fish. Figure 1, taken from Jackson and Starrett 
(1959: 162) shows that wind had little effect on the turbidity of Lake 
Chautauqua when vegetation was present, and a marked effect when vegetation 
was absent. 

Aquatic macrophytes provide habitat for fishes and for a group of inver- 
tebrate animals called the "weed fauna." Yellow perch may have disappeared 
from the bottomland lakes along the Illinois River due to the loss of plant 
beds the perch use for spawning. Smith (1971: 8) indicates that populations 
of the bigeye shiner, the bigeye chub, and the pugnose minnow have been 
decimated in Illinois streams primarily because of the disappearance of 
aquatic vegetation. The "weed fauna" consists of snails and insects which graze o 
the macrophytes themselves or on the "scum" formed by bacteria and algae 
on the larger plants. Predatory insects such as dragonfly and damselfly 
nymphs hunt their prey among the leaves. The "weed fauna" is important because 
it furnishes food for members of the sunfish family, such as largemouth bass 

and bluegill. In bottomland lakes along the Illinois River, the biomass of 
the weed fauna once averaged 2118 lbs. to the acre (2374 kg/h) and was eight 
times greater than the biomass of bottom fauna (Richardson, 1921: 431-432). 
Since the late 1950' s and early 1960's there has been no v;eed fauna in these 
lakes because the weeds cannot gain roothold in the soft bottom which is con- 
stantly disturbed by wind-generated waves and also because light penetration 
has been reduced by turbidity. The turbidity and degraded bottom are caused 
by sediiuent. 

The source of the sediment in the Illinois River cannot be attributed 
to municipal and industrial effluents originating in the Chicago-Joliet area, 
because the upper Illinois River is less turbid than the lower Illinois. 
In fact, beds of sago pondweed grow in the Des Plaines River below the entrance 
of the Chicago Sanitary and Ship Canal. The Des Plaines and Kankakee Rivers 
join to form the upper Illinois River. It is only further downstream where 
tributaries which drain extensive agricultural areas begin to join the Illinois 
that the turbidity increases and no submerged vegetation occurs. 

Reduction of Visibility 

Aquatic organisms use a variety of senses to locate food and mates and 
to avoid danger. The game fishes rely heavily on sight in hunting their 
food, and it is this attribute which contributes to their desirability as 
game fish, for they will strike at artificial lures. 

If the turbidity of water is increased due to suspended sedinent, the 
ability of game fish to find food (or strike at lures) is reduced. The 
distance at which a fish will sight and react to prey or bait is called the 

reactive distance, and depends on both the size of the prey and the tur- 
bidity of the water. Vinyard and O'Brien (1976: 28A6-2847) found that the 
larger the prey size, the greati^r the effect of turbidity in reducing the 
reactive distance of bluegills. A turbidity increase from 6.25 to 30 JTU 
reduced the reactive distance from 8.5 to 2.5 cm for prey 1 mm in size and 
from 37.5 to 6.0 cm for prey 2.5 mm in size. Thirty JTC appeared to be 
an upper limit for a turbidity effect. Turbidities greater than 30 JTU did 
not further reduce the reactive distance presumably because the fish stopped 
relying on sight to locate their prey and were forced to rely on another 
sensory system, such as the lateral line system, which is sensitive to water 
pressure waves generated by movements of prey. 

Reduction in reactive distance du(i to turbidity can have a major impact 
on the feeding of game fish. Prey that move out of a fish's reactive 
distance have in fact escaped, and the predator must begin a search for 
food again. Reduction of reactive distance greatly lim.its the volume of 
water a fish can search in a given time. For example, a 50 percent reduction 
In reactive distance reduces the actual volume searched by a factor of 4, 
if the fish is assumed to be searching a cylinder, and by a factor of 8, if 
the fish is assumed to be searching a hemisphere or a sphere (Vinyard and 
O'Brien, 1976: 2848). 

The significance of the laboratory findings of Vinyard and O'Brien 
(1976) is that turbidity can reduce the feeding of game fish even if there 
is an abundance of food available in tlie water. 

The reduction in reactive distance of game fish due to turbidity also 
has a marked impact on angling success, as sho\m belov; for Fork Lake, in 
Macon County, Illinois during the Marcli through September, 1938 fishing 
season (Bennett, Thompson, and Parr, 1940: 22): 

Secchi Disk 


of Fish Cs 

Visibility, Feet 

Per Man-Hour 

3.5 to 4,5 


2.0 to 2.5 


0.5 to 2.0 


Reduction of Catch in 
Relation to Catch \-Jhen 

3.5 to 4.5 


Many species of game fish exhibit complex reproductive and social 
behavior which depends on visual cues. For example, male sunfishes build 
nests in shallow water at the beginning of the breeding season. Since the 
number of males may exceed the number of favorable nesting sites, and since 
the fish seem to nest in colonies, each nale must aggressively defend his 
nest against other males. At the same time, the male must be prepared to 
accept ready females into his nest for spawning. The distinction between 
a rival male and a ready female is based on visual cues. A female appraoches 
the nest slowly in a submissive posture, with fins clamped, and her skin 
assumes a characteristic washed-out color pattern. A rival male generally 
moves rapidly, raises his fins, and exhibits a bold color pattern. A 
reduction in visibility interferes with these visual cues. Heimstra et al. 
(1969: 5-8) found that the activity levels of largemouth bass were reduced and 
normal social behavior of green sunfish iias altered in moderately turbid water 
(1^-16 JTU) . The fish also coughed and scraped themselves against the sides 
of the tanks more frequently in the moderately turbid water (Heimstra et al., 
1969: 8). 

Abrasion and Clogging 

Most aquatic organisms can tolerate sediment in water for a period of 

time. Wallen (1951: 18) found that the following turbidity levels (in JTU) 

were required to kill fish: 

Rock bass 38,250 

Pumpkinseed 69,000 

Channel catfish 85,000 

Largemouth bass 101,000 

Black crappie 145,000 

Green sunfish 166,500 

Fish exude a protective mucus on their skin and gills which traps and con- 
tinually flushes away particles. Mussels have a protective mucus on their 
gills and can close their shells. There is a group of caddisflies which 
feed by spinning nets into which particles of food are washed by water 
currents. These caddisflies then eat the net, food and all. If one 
net becomes clogged with sediment, the caddisflies presumably can spin 

However, all of the above protective mechanisms are temperary measures. 
Continual production of mucus by the fish requires metabolic energy and 
constitutes a stress on the fish at the same time that its ability to find 
food is reduced by turbidity. If the net of the caddisfly is continually 
clogged with sediment of little or no nutritional value, the caddisfly will 
eventually starve. Clams can resist temporary unfavorable conditions by 
closing up, but then they cannot carry on normal activities such as feeding, 
aerobic respiration, growth, and reproduction. 

Therefore, while some adult organisms can withstand enormous amounts of 
sediment in water for several day:; or weeks, the population may eventually 
die out due to starvation, failure of rejiroduction, or cumulative stress. 

For exam.ple, Ellis (1936) found that the defenses of mussels against 
excessive sediment were eventually overwhelm.ed after a long period of exposure. 

Silt interfered with the feeding of the mussels and caused mortality: 

These experiments, extending over some fourteen months, showed 
that most of the common fresh-water mussels were unable to m^ain- 
tain themselves in either sand or gravel bottoms when a layer of 
silt from one-fourth of an inch to one inch deep was allowed to 
accumulate on the surface of these otherwise satisfactory bottom 
habitats, although other individuals of these same species held in 
the lattice-work crates a few inches or feet above the bottom 
thrived in this same water. Daily analyses of the water at 
various levels in these raceways shewed that the high mortality 
of the mussels on the bottom was induced by the silt covering 
and was not due to low oxygen, pH, carbonates or other water con- 
ditions. The Yellow Sand-shell (Lampsilis anodontoides ) , a sand 
inhabiting species was the most readily killed by silt deposits, 
and the Three-horned Warty-back, Obliquaria ref lexa , the Maple 
Leaf, Quadrula guadrula , and the Monkey-face, Quadrula metanevra , 
were among the m.ore resistant. However, the mortality rapidly 
approached 90 percent or more for all species when the silt 
layer began to permanently cover the sand or gravel. On the other 
hand the mortality of the mussels in the crates was very low. 

Laboratory experiments with fresh-water mussels in water 
carrying heavy loads of erosion silt (this material being kept in 
suspension by automatic glass stirring devices) showed that 
erosion silt interfered with the feeding of fresh-water mussels. 
The mussels in the muddy water remained closed a large percent 
of the time, 75 to 95 percent, v;hile mussels in silt-free water 
but subject to the same current influences as those in the erosion 
silt tests V7ere closed less than 50 percent of the time. When 
mussels opened in water carrying large amounts of erosion silt 
an excessive secretion of mucus was produced and this served in 
part to remove the silt which tended to settle into the mantle 
cavity. Mussels dying In silt-laden water always contained 
deposits of silt in the mantle cavity and frequently in the 
gill chambers. (Ellis, 1936: 39-40. Material in parentheses 
inserted by Sparks.) 

It is noteworthy that the yellow-sand-shell was most readily killed 

by silt deposits in Ellis's experiments, and that it has apparently 

disappeared from the Illinois River, probably due to increased silt loads 

(Starrett, 1971: 334). The silt-resistant maple-leaf and three-horned 

warty-back were still found in the Illinois River in 1966 (Starrett, 1971) 

Habitat Alteration and Destruction 

Sediment deposits can cover gravel and sand bottoms which many organisms 


require for carrying on normal activities such as feeding and reproduction. 
In extreme cases, sediment can completely fill, and thereby destroy, an 
aquatic habitat. 

Smith (1971: 8) states that "the gravel chub, Ozark minnow, weed shiner, 
western sand darter, banded darter, and slenderhead darter have reduced 
ranges because they have lost extensive gravel- and sand-substrate habitats 
to silt," 

The formerly productive bottomland lakes along the Illinois River 
are almost completely filled with sediment. In February, 1976, the 
Illinois Natural History Survey made a survey of the water depths of Lake 
Chautauqua, a bottomland lake along the Illinois River at Havana in Mason 
County. The maximum depth of the southern 2/3 of this large lake (2000-3000 
acres, depending on water levels) was 18 inches. The findings were analyzed 
by the Illinois State Water Survey, and compared to their earlier studies 
of sedimentation in Lake Chautauqua (Stall and Melsted, 1951). In the 
period from 1926-1976, Lake Chautauqua has lost 34.7% of its original capacity. 

The loss in terms of fish habitat is much worse than the capacity loss 
indicates, because the deeper areas of the lake have filled much faster than 
the shallow areas, and the lake is now uriformly shallow. It once contained 
areas which were 7 feet deep during low water stages. A diversity in the 
topography of the bottom is important in maintaining a diversity of plant and 
animal life. The deeper the water, the less the light penetration, and 
different species of aquatic plants are adapted to different light intensi- 
ties. In very deep areas, there are holes in the mat of vegetation because 
plants are absent or their growth is reduced. As many fishermen know, large 
gamefish often inhabit the edge of these holes. The deep areas also 


offer a refuge for fish both in winter, when shalloxij water freezes solid, and 

in sunuraer, when the water temperature in shallow areas can approach lethal levels, 

In the summer of 1975, the Illinois State Water Survey measured sedi- 
ment deposition in Lake DePue , a 500-acre bottomland lake along the Illinois 
River in Bureau County. Their findings were as follows (Lee and Stall, 1976:11): 

(1) From 1903 to 1975 the capacity of Lake DePue has been 
reduced from 2837 ac-ft to 778 ac-ft, a 72.6% capacity loss. 
In terms of annual deposition rate, the lake lost 28.6 ac-ft 
or 1.01% per year. 

(2) The change of lake volume is c'ue to the rising of the lake 
bed. It was estimated that the annual rate is 0.57 inches per 
year. The expected time to r<?ach the current normal lake level 
is about 33 years. 

The latter finding indicates that there will be no lake at all in 33 years. 

As to the source of the sediment in the lake, Lee and Stall (1976: 29) 

conclude that it comes from the suspended sedim.ent load carried by the 

Illinois River. According to local residi^nts, the former depth of Lake 

DePue was about 18 or 20 feet (Lee and Stall, 1976: 2) and annual speedboat 

races and regattas were held there. The Last annua] speedboat race was in 

1973, and the 1974 race was cancelled because the water was too shallow 

(Sparks, 1975: 62). 

Lake Meredosia, a lAOO-acre lake along the Illinois River in Morgan 
and Cass Counties, has lost 46% of its capacity since 1903 (Lee, et al., 
1976: 7). 

In the summer of 1976, a Natural History Survey crew attempted to 
sample 7 additional bottomland lakes along the Illinois River. It was 
impossible to float a canoe in more than about 1/3 of the surface area of 
each of these lakes, due to extens;ive sediment deposits. 

There is evidence that the rate of sedimentation in these lakes is 
greater in recent times than it has been in the past. Figure 2 shows that 


Figure 2 

1926 ■ 1950 AND 1850 ■ 1976 


2 3 4 



In August 1974, dissolvecl cxygc" levels in Meredcsia Lake were 3 mg/1. 
while oxygen levels in the river on the same date were 6 mg/l. The read- 
ings were taken in the middle of the afternoon on an overcast day, and 
waves produced by a strong v;ind were resuspending botton sediments in the 
lake. In the lake, a die-off of gizzard shad was occurring, and almost all 
the fingernail clams maintained in plastic cages on the bottom of the lake 
had died since they had last been checked in mid-July. 

Metals are known to accumulate in sediment. For example, Mathis and 
Cummings (1973: 1580-1581) found that most metals in the Illinois River 
occurred in sedim.ent at levels several orders of magnitude greater than 
levels in water. Organisms which livec In the sediment, such as oligochaets 
worms and clams, contained higher levels of the metals than organisms such 
as fish. Since the chemical environment in the gut of a worm or at the 
gill surface of a clam is different than it is in the sediment or water, 
it is possible that m.etals and other toxicants can be mobilized from the 
sediment and taken up by organisms which ingest sediment or live in contact 
with sediment. 

Sediment can serve as either a source or a sink for nutrients such as 
phosphorus, depending upon conditions such as pH, temperature, oxidaticn- 
reduction potential, and the amount present in water. 

Ecosystem Effects 

The plants and animals living together in a certain habitat form a 
characteristic assemblage of species called an ecosystem^ and one dramatic 
effect of excessive sediment can be to cause a shift froui one type of eco- 
system to another. For example, sediment very likely contributed to the 


at depths greater than 2 feet below an arbitrary reference point of A35 feet 
above mean sea level (>fSL) , the rate of sedimentation in Lake Chautauqua has 
been greater in the period 1950-1976, than in the p?.riod 1926-1950. For 
example, at a depth of 5 feet, the 1926-1950 rate was . OA inches per year, 
while the 1950-1976 rate was approximately .06 inches per year. It is 
necessary to compare rates for the two periods at the same depth, because as 
was mentioned earlier, the rate of sedimentation increases with depth. 
The reason that there is a negative rate of sedimentation in v/ater depths 
less than two feet is that shoreline and islands in these lakes have eroded 
as a result of wave action. The wave action has probably been more severe 
since the aquatic vegetation in these lakes disappeared in the 1950' s 
(see Figure 1) . 

Six other bottomland lakes along the Illinois River showed much the same 
pattern as Lake Chautauqua: the rate of sedimentation has increased in recent 
periods compared to older periods going as far back as 1903. While the navi- 
gation dams installed on the Illinois River in the 1930' s have slowed the 
current and increased sedimentation and while boats using the navigation 
channel resuspend bottom sediments, the input of sediment to the river m.ay also 
have increased in recent times, because sedimentation rates have increased 
in lakes such as Chautauqua which are upstream from the influence of the 
dams and which are connected with the river only during high water. 

Backwater areas along the Minsissipi i River bordering Illinois are also 
filling in noticeably, although the process seems to bs taking longer than it 
has in the Illinois River, perhaps becau;;e the Mississippi is a much larger 
river than the Illinois. 

The loss of bottomland lakes along the Illinois and Mississippi Rivers 
represents loss of the majority of lake habitats available in Illinois. 


Tiie only natural lakes in Illinois are Lake I'iciiigan, the lakes in the glaci- 
ated lands of northeasterr- Illinoj-?, and the bottonLLand lakes along the 
Illinois and Mississippi Rivers. 

Sedimentation rates for res irs in various parts of the state are 
given in the suBmaj-y report of t1; . Soil Erocicn and Sedirnentation Subcommittee. 
The rates range from 0.28 to 7.7 tons of reservoir sediment per year per acre 
of watershed. The useful life span of these reservoirs, in terms of producing 
fish and aquatic life, is shortened in proportion to the rate of sedimentation, 
just as the useful life span for water supply is shortened. 

Interactions Between Sediment and Other F .'.ctors 

Ellis (1936) found that organic matter mixed with erosion silt created 
an oxygen deuianu in water and that the oxygen demand \-;as maintained 10 tn 15 
times as long as the oxygen demand created by the same amiount of organic ma- 
terial mixed with sand. The ox>'gen demand can increase many-fold when sedi- 
isent containing organic material and bacteria is re.suspended by waves or 
currents (Butts, 197A; Baumgartner and Palotas, 1570). For example. Butts 

(197A) found that under quiescent conditions the sediment ox^'gen dei^iand in 

the Illinois River at miJe 198.8 in Peoriu Pool was 2.8 g/m /day, while the 

demand was 20.7 g/m /day when the sediment v;as disturbed. At three sampling 

stations in Meredosia Lake (mile 72-78) the sediment oxygen demand under 

quiescent conditions ranged from 2.58 to A. 32 g/m'/dayj and frcmr 12^92 to 

83.0 g/ffi /day under disturbed conditions (Personal Communication, 2 September 

1975, Mr. Thomas A. Butts, Assoriare Professional Scientist. Illinois State 

yatpr Survey. Peoria. Illinois). Trie oxygen demand exerted by sediment in 

some of the river and '-r- poTr-c bot^omiand iakRS is grest -rrif'sjgh tn seriouslv 

dimirijsh the oxygen supply' in the water. 

In August 197^, dissolved oxygen levels in Meredosia Lake were 3 mg/1. 
while oxygen levels in the river on the same date were 6 mg/l. The read- 
ings were taken in the middle of the afternoon on an overcast day, and 
waves pre ed by a strong wind were resuspending bcttcn sediments in the 
lake. In .he lake, a die-off of gizzard shad was occurring, and almost all 
the fingernail clams maintained in plastic cages on the bottom of the lake 
had died since they had last been checked in mid- July. 

Metals are known to accumulate in sediment. For example, "Mathis and 
Cuinmlngs (1973: 1580-1581) found that most metals in the Illinois River 
occurred in sediment at levels several orders of magnitude greater than 
levels in v/ater. Organisms which livec' in the sediment, r :ch as ollgochaets 
worms and clams, contained higher levels of the iretais than organistis such 
as fish. Since the chemical environment in the gut of a worm or at the 
gill surface of a clam is different than it is in the sediinent or water, 
it is possible that metals and other toxicants can be mobilized from the 
sediment and taken up by organi-sms which ingest sediment or live in contact 
with sediment. 

Sediinent can serve as either a source or a sink for nutrients such as 
phosphorus, depending upon conditions such as pH, temperature, oxidation- 
reductioa potential, and the amount present in water. 

Ecosystem Effects 

The plants and aninals living together in a certain habitat form a 
characteristic assGiriblage of species called an ecosystem, and one dramatic 
effect of excessive sediment can be to cause a shift from one type of eco- 
sj^steiu to another. For example . sediment very likely contributed to the 


shift in the numerous bottomland laker, along the Illinois River from clear, 
vegetated waters with abundant gane fish populations to turbid, vegetation- 
less waters dominated by species such as carp and buffalo (Sparks, 1975: 54-56) 

The presence ot sediment brings about these changes in both direct and 
indirect ways, some of which have been mentioned above, Th.e relationship 
between sediment and an obser\'ed change in an ecosystem is often complex, 
and some examples of these complex cause-and-ef f ect patterns will be discussed 

As mentioned above, the reactive distance of predatory fish is reduced 
by turbidity. In addition, populations of prey used by gamefish generally 
decline in turbid water. For exaniple. Buck (1956a: 49) found that the ratio 
of forage fishes (gizzard shad, minnows, and small sunfishes) to the predaceous 
bass and crappie was approximately 1 to 1 in a muddy reservoii and 13 to i in 
a clear reservoir. As a consequence, the growth of bass, crappies, and other 
carnivorous species in the turbid reservoir severely limited. The popu- 
lations of plankton-feeding forage fish, such as gizzard shad, were limited 
due to the low level of plankton production in the turbid reservoir (Buck. 
1956a: 51). 

Sediment can change the species com.position of a body of water by changing 
the habitats the food supply, and bringint about differential rates of repro- 
duction in different species. Foi example, the sunfishes, a family which in- 
cludes largemouth bass, bluegill. and crappieS; lay their eggs in nests which 
are constructed in shallow water. They prefer to construct nests en firm, 
rather than soft substrates^ Buck (1 956a r 23) found that large-mouth bass and 
sunfish produced young in new farm ponds with firm, unsllted bottoms^ but not 
in older ponds with soft, silt-lacen bottoms. The sunfishes must be able to 
see their TEatec re go through the reprodictivc act, which is mediated by visual 


cues. The males fan Lheir eggs to keep away sediment and supply oxygenated 
water. The eggs can be sr-othered by excessive sedirient-. The guardian maJe 
must also be able to see In order to keep av7ay suckers and rdnnows which eat 

Juvenile gamefish take refuge in plant beds and feed on the insects and 
other "weed fauna" they find there. Older gamefish feed on forage fisli, 
which in turn are dependent on the plankton, which is less abundant in 
turbid waters than in clear water. 

The end result of the complex interactions described above v?ere observed 
by Buck \i956b) , who studied fish product Lon in fann ponds ^ hatchery ponds-, 
and reservoirs in Oklahoma which had a wide range of turbidities. The farm 
ponds were rotenoned, then restocked with largemouth bass and bluegllls or 
largernouth bass and redear sunfish, A total of 12 farm ponds v;as divided into 
3 turbidity classes. After two growing seascns, the cverage total weights of 
fish were: 

clear ponds (less than 25 JTU) i&i.5 jb/acre 

intermediate ponds (25-100 JTU) 9A.0 lb/acre 

touddy ponds (100 JTU) 29.3 lb/acre 

"Tl. 1 J 1.1 -• T 1 fJ_U ».,«».^J..„.,^' ™«>-^ oK.-r^^ or.^^ 1. ctr,A rrr^l.! factor- 
ill clear vater. Survival of bass was greater in internedlate poTid? than in 

clear ponds, perhaps due to competition vlth abundant smifish populations in 

the clear ponds. However, the surviving bass grew faster in clear ponds: 

average average 

weight length 

clear ponds i'i.Ox 6.9 in. 

intermediate ponds 7.1 x 5.1 in. 

auddj pcads 2.5x 2,^ Ir., 


The results from hatchery ponds, where turbidities were artificially con- 
trolled, and from the reservoirs, generally paralleled the results from the 
farm ponds. 

In the turbid reservoir. Buck (1956b: 257) found an unusual preponderanc( 

of old bass and a scarcity of young bass — this was very unusual for a new 


For example, of 56 bass collected in 1954^ 64 percent were in their 

sentative of all samplings. Ail evidence points to a small popu- 
lation dominated by slow-growing-, older bass and with limited 
recruitment through, natural reproduction. It seems doubtful that 
the bass population will be able to sustain itself in the face of 
increasing turbidities. 

In contrast, young-of-the-year bass ware abundant in the clear 
reservoir both years of the study. To illustrate, the population 
of flngerling bass in a 10-acre cove roteuoned in 1955 was estimatec; 
conservatively at 21,780. 

Buck observed the same pattern in the other gamefish. In contrast, 

catfish and rough fish were favored in the turbid waters (Buck, 1955b: 257): 

Both channel catfish and flathead catfish are abundant in the 
turbid reser\'cir. In the clear reservoir, only two adult channel 
catfish and one adult flathead were taken. In the first year of 
clear reservoirs, the bass, crappies, and other scaled species 
apparently out-produce the catfish ^nd then limit them by predation 
on their young. Turbid waters, on the other hand, offer young 
catfish protection from these predators. Furthermore, catfish 
can find food in turbid waters more easily than can species which 
do not have so highly a developed sense of smell. As a result, 
the bass and crappies lose ground. Even growth of the channel 
catfish, however, was slower in the turbid reservoir than In less 
turbid waters. Flathead catfish exhibited the most favorable 
growth of any species studied in the turbid reservoir, reaching 
an average length of 28.3 inches in their fourth year. 

The combined weight of rough fish (carp, river carpsuckers^ and bullheads) 
represented 42.4 percent of the population by weight in the turbid reservoir, 
com.pared with 7.0 percent in the clear rt.'servoir. 

Buck's (1956b: 260) final conclusion was: "The clear reservoir at- 
tracted more anglers, yielded greater returns per unit of fishing effort:, es 


well ns more desirable species, and was iirineasurably more appealing In the 
aesthetic sense." 

The same causal relationships and end i-er.ults Buck observed in the Okla- 
homa ponds and reservoirs have occurred in Illinois. The bottomland lakes 
along the Illinois River have changed from clear, vegetated waters which 
supported an abundance of gamefish, commercial fish, and waterfowl, to turbid, 
vegetation-less waters dominated by carp and buffalo. In socie cases the 
lakes are so filleu with sediment the carp, buffalo, and gizzard shad do not 
survive. The sediment not only fills the lakes, but also exerts an oxygen 
demand v;hich depletes the dissolved oxygen required by fish and other aquatic 

At one time, special trains brought sport fishermen to to\«is, such as 
Havana, along the Illinois River, and freight trains hauled £v;ay commercial 
fish to Chicago and New "iork (Milis, et al. , 1966-. 14). Now, Dixon's fee 
fishing area in Peoria imports carp from Wisconsin, the restaurants along 
the Illinois River buy channel catfish from Arkansas, and the residents of 
beach communities, such as Quiver Beach and Baldwin Beach, in Mason County , are 
no longer able to swim. In the bottomland lakes or even to launch their boats 
from their cottages in mid-summer. 

Tabic 1 
Reported Levels of Effect of Sediment and Turbidity on Aquatic Life 



20 JTU 

B iological Effect 

Largemouth bass activity reduced and 
social behavior of green sunfish altered. 
Coughing and scraping increase. 

Reactive distance of bluegill reduced by 
50%, in comparison to reactive distance 
in clear water. 


Heimstra et al. , 
1969; 5-8. 

Vinyard and O'Brien, 

1 Q 7 £ . 0/7 

30 JTU Reactive distance of bluegill reduced by 
80%. Upper limi t for effect on bluegill 
react-ive distance. 

Vinyard and O'Brien, 
1976: 2S47 



Su% reduction in net plankton^ comparec 
clankton production in clear farm pond; 
( 25 JTU). 

'laffcv, 1955: 43 


f;-i JTU 

90% reduction in net Dlankton. compared 

to plankton prod-, 
ponds C 25 JTU) 

in clear farm 

Highest turbidity in which largemouth 
bass were able to spawn. 

Claffey, 1955: 43 

Buck, iS56a: 
19, 23-24 

100 JTU Spawning success of redcar and bluegill Buck; 1956a; 
severely restricted or completely 23-24 

restricted above this level. 

25-100 42% reduction in total weight of largemouth i 
JTG bass, redear sunfish, and bluegills produced 

in farm, ponds, relative to total production 
in clear farm ponds. 49% reduction in aver- 
age weight gain and 26% reduetion in average 
length increase of young bass after two growing 
seasons, in comparison co gains by bass in 


100 JTU 82% reduction in total weight of largemouth Buck, 1956b: 249 
bass, redear sunfish, and bluegills produced 
in farm ponds, relative to total production 
in clear farm ponds, 82% reduction in average 
weight gain and 65% reduction in average length 
increase of young baf.s after two growing seasons, 
xii COuipaixsOu to gains by \>czg ir. c3 53.r ponds. 

Table ] (continued) 
Reported Levels of Effect of Sediment and Turbidity on Aquatic Life 

Level Biolo gical Effect Reference 

An increase 26% increase in raacroin/ertebrate drift. Gaumion, 1970 : 

in suspended 68,96 



duet) from 9.7 

to 28. 3 uig/1 

An increase 90% increase in macroinvertebraLe drift. Gammon, 1970: 

in suspended 68, 96 



dust) froir. 20.3 

to 125.0 mg/1 

38,250 JTU Lethal to rock bass. Wallen, 1951: 18 

85,000 JTU Lethal to channel catfi;;h. Vsllen, 1951; 18 

101,000 JTU Lethal to largemouth bass. Vallen, 1951: 18 

Literature uited 

Baumgartner , D.J., and G. Palotas. 1970. The oxygen uptake demand of 

resuspended bottoui sediments. U.S. Environrriental Protection Agency, 
Water Pollution Control Research Series 16070 DCD 09/70. U.S. 
Governr.ent Printing Office. Washington, D.C. 

Bennett, G.W. , D.H. Thoir.pson, and S.A. Parr. 19A0. A second year of 
fisheries investigations at Fork Lake, 1939. Illinois Natural 
History Survey Biological Notes No. U. Urbana, Illinois. 24 p. 

Buck, D.H. 1956a. Effects of turbidity on fish and fishing. Oklahoma 

Fisheries Research Laboratory Report No. 56. Norman, Oklahoma. 62 p. 

. i956b. Effects of turbidity on fish and fishing. Transactions 

of the T\-7enty-First North Ajnerican Wildlife Conference. Wildlife 
Managenient Institute. Washington, D,C, pp. 2A9-26i. 

Butts, T.A. 1974. Measurements of sediment oxygen demand characteristics 
of the Upper Illinois Water^-.'ay. Report of Investigation 76. Illinois 
State Water Survey. Urbana, Illinois. 32 p. 

Ciaffey, F.J. 1955. The productivity of Oklahoria waters with special 
reference to relationships betv?eeri turbidities from soil, light 
penetration, and the populations of plankton. Thesis. Oklahoma 
A and M College. 102 p. 

Ellis, M.M. 1936. Erosion silt as a factor in aquatic environments. 
Ecology 17: 29-42. 

Gammon, J.R. 1970. The effect of inorganic sediment on stream biotti. 

U.S. Environmental Protection Agency, Water Pollution Control Research 
Series 18050 DWG 12/70. U.S. Government Printing Office. Washington. 
D.C. 141 p. 

Heimstra, N.W. , D.K. Damkot, and N.G. Benson. 1969. Some effects of silt 
turbidity on behavior of juvenile largemouth bass and green sunfish. 
Technical Papers of the Bureau of Sport Fisheries and Wildlife No. 20. 
U.S. Department of the Interior, Fish and Wildlife Service. Washington, 
D.C. 9 p. 

Jackson, H.O,, and W.C. Starrett, 1939, Turbidity and sedimentation at 

Lake Chautauqua. Illinois. Journal of Wildlife !Ianagement 23: 157-168. 

Lee, M.T. 1975. Sediment deposition of Lake Chautauqua^ Havana, Illinois. 
Illinois State Water Survey. Urbana, Illinois. 9 p. 

, and J.B. Stall. 1976. Sediment deposition in Lake DePue, DePue, 

Illinois and its implications tor future lake management. Illiuuj 
State Water Survey. Urbana, Illinois. 31 p. 

, 2nd T=A- Butts. 1976. Tha 1975 sediraent survey of 

Lake Mereaosia, .'eredosia, liiinois. liiincit; State V/Hter :iur'.'ey. 
Urbana, Illinoi- . 23 p. 

Mathis, B.M. , and T.F. Cuinmings. 1973. Selected metals in sediments, 
vater, aad biot.- in the lilincis River. journal Water Pollution 
Control Federation 45(7): 1573-1583. 

Mills, H.B., W.C. Starrett, and F.C, Eellrose. 1966, Man's effect on 
the fish and vjilalife of tlie Illinois River. Illinois Natural 
History Survey ^riological Notes No. 57. Urbajia, Illinois. 2A p. 

Richardson, R.E. 1921. The small bottom and shore fauna of r.he middle 
and lov;er Illinois River and its connecting lakes, Chlllicothe to 
Grafton: it? v.-Aluation; its sources of food supply; and its 
relation to the fishery. Illinois State Natural History Survey 
Bulletin 13(15) • 363-522. 

Smith, P.W. 1971. Illinois streams: a classification based on their 
fishes and an analysis of factors responsible for disappearance of 
native species. Illinois Natural History Survey Biological Notes 
No. 76. Urbana^ Illinois. 14 p. 

Gparkij. R.E. 1S75. Environrnental inventory and assesf^iaent of navigation 
pools 2^, 25, and 26, upper Mississippi and lower Illinois Rivers: 
An electrof ishing -survey of the Illinois River. U.S. Army Engineer 
Waterways rxperi^.ent Snaticn, Fnviron:nentaj Effects Laboratory. 
Vicksburg, Mississippi. 121 p. 

Stall, J.B.s and S=W, MeJsted, 1951. The silting of Lake Chautauqua, 

Havana. Illinois. Report of Investigation 8, Illinois State Water 
Survey, in cooperation with Illinois Agricultural Experiment 
Station. Urbana, Illinois 15 p. 

Starrett, V.C. 1971. k survey of the m.ussels (Uninna cea) of the Illinois 
River: a polluted stream. Illinois Natural History Survey Bulletin 
30: 267-^03. 

Vinyard, G.L. , and W.J. O'Brien. 1976. Effects of light and turbidity 

on the reactive distance of bluegill (Lepo mis macro c h irus) . Journal 
of the Fisheries Research Board of Canada 33: 2845-28/^9.' 

Wallen, E.I. 1951. The direct effect of turbidity on fishes. Bulletin 
Oklahoma Agricultural and Mechanical College. Series 2, Ko. •^8. 
26 p. 



Effects of SedimenC on Aquatic Life 

Prepared by 

Richard E. Sparks 

January A, 1977 

The plants and animals living on the bottom of a stream or lake, 

FTU . Formazine turbidity units . Turbidity as determined in a nephelometer 

which has been calibrated with a suspension of formazine as a turbidity 
standard. Formazine is formed by reacting hydrazine sulfate and hexa- 
methylcnc tetramine under carefully controlled conditions (Chevalier, 
1959: 132-133). 

Jackson candle turbidimeter . A turbidimeter which measures "the depth of a 
column of water sample that is just sufficient to extinguish the image 
of a burning standard candle observed vertically through the sample." 
Results are expressed as Jackson turbidity units (JTU) (American Society 
for Testing and Materials, 1973: 232). 

JTU . Jackson turbidity units. 

Nephelometer . A turbidimeter which measures "the light-scattering charac- 
teristics (Tyndall effect) of the particulate matter in the sample. 
. . . The measurement of nephelometric turbidity is accomplished by 
measuring the intensity of scattered light at 90 deg to the incident 
beam of light. Numerical values are obtained by comparison with the 
light-scattering characteristics of a known or an arbitrarily chosen 
material in an equivalent optical system. Comparison may also be made 
between transmitted light effect and scattered light effect." The 
results from a nephelometer are sometimes expressed as nephelometric 
turbidity units (NTU) (American Society for Testing and Materials, 1973: 

NTU . Nephelometric turbidity units. 

Particulate matter . Same as suspended matter and total suspended solids. 

The amount of material in suspension, determined by measuring the weight 
gain of a filter after a known volume or weight of the water sample 
has passed through it. 

Photosynthetic zone . Same as euphotic zone. The depth of water in which 

there is enough light for photosynthesis to exceed respiration (Odum, 
1971: 14). In general, this zone extends down to the depth where 
the light intensity is 1 percent of full sunlight intensity (Odum, 
1971: 301). 

Sparks Glossary paf 

^ Phytoplankton . Microscopic, drifting aquatic plants, mostly algae. 

Resuspended sediment . Sediment which is stirred up from the bottom by 

water currents, wave action, boat traffic, or by the rooting activities 
of fish such as carp. 

Secchi disk . A circular metal plate, 20 cm in diameter, the upper surface 
of which is divided into four equal quadrants and so pointed that the 
two quadrants directly opposite each other are black and the inter- 
vening ones white. The disk is used to measure the limit of visibility 
in water by lowering it into the water on a graduated line, and noting 
the depth at which it disappears (Welch, 1948: 159). Secchi disk 
transparency represents the zone of light penetration down to about 
5 percent of the solar radiation reaching the surface and marks the 
lower limit of the major photosynthetic zone (Odum, 1971: 297). 

Sediment . Solid, particulate material which is deposited by water. 

Submergent vegetation . Large free-floating or rooted aquatic plants which 
are entirely submerged in the water, such as coontail, or which have 
leaves at the surface of the water, such as lotus. In contrast, 
emergent vegetation refers to plants such as cattail, which can grow 
in shallow water, but which have leaves above the water. 

Suspended sediment . Sediment which is carried in the water column. 

Turbidimeter . A device for measuring turbidity. 

Turbidity . "Turbidity in water is caused by the presence of suspended matter, 
such as clay, silt, finely divided organic and inorganic matter, plank- 
ton, and other microscopic organisms. Turbidity is an expression of 
the optical property that causes light to be scattered and absorbed 
rather than transmitted in straight lines through /a/ sample /of watery. 
Attempts to correlate turbidity with the weight concentration of sus- 
pended matter are impractical because the size, shape, and refractive 
index of the particulate materials are important optically but bear 
little direct relationship to the concentration and specific gravity 
of the suspended matter." (Rand, 1976: 131.) 

Zooplankton . Microscopic, drifting aquatic animals. 

Sparks Glossary page 3 

Literature Cited 

American Society for Testing and Materials. 1973. 1973 Annual book of 
ASTM standards, part 23, water, atmospheric analysis. American 
Society for Testing and Materials, Philadelphia, Pennsylvania. 1108 p. 

Chevalier, P. 1959. Formazine standard for turbidity. Brasserie 152: 132-133. 

Odum, Eugene P. 1971. Fundamentals of ecology. Third edition. W.B. Saunders 
Co., Philadelphia, Pennsylvania. 57A p. 

Rand, M.C., Arnold E. Greenberg, and Michael J. Taras, editors. 1976. 
Standard methods for the examination of water and wastewater. 
Fourteenth edition, /jnerican Public Health Association, Washington, 
D.C. 1193 p. 

Welch, Paul S. 1948. Limnological methods. McGraw-Hill Book Co., New York. 
381 p.